Enable renderer-side mixing output of different audio sources basing on finch

content/renderer/media/audio_device_factory.cc

Index: content/renderer/media/audio_device_factory.cc
diff --git a/content/renderer/media/audio_device_factory.cc b/content/renderer/media/audio_device_factory.cc
index af6ddbe18517603da9da3e48b18ab1fac458e51b..fd5aaadb4da6e2397f778dfae88de86f7f551157 100644
--- a/content/renderer/media/audio_device_factory.cc
+++ b/content/renderer/media/audio_device_factory.cc
@@ -15,6 +15,7 @@
 #include "media/audio/audio_input_device.h"
 #include "media/audio/audio_output_device.h"
 #include "media/base/audio_renderer_mixer_input.h"
+#include "media/base/media_switches.h"
 #include "url/origin.h"
 
 namespace content {
@@ -48,9 +49,8 @@ bool IsMixable(AudioDeviceFactory::SourceType source_type) {
   if (source_type == AudioDeviceFactory::kSourceMediaElement)
     return true;  // Must ALWAYS go through mixer.
 
-  // TODO(olka): make a decision for the rest of the sources basing on OS
-  // type and configuration parameters.
-  return false;
+  // Mix everything if experiment is enabled; otherwise mix nothing else.
+  return base::FeatureList::IsEnabled(media::kNewAudioRenderingMixingStrategy);
 }
 
 scoped_refptr<media::SwitchableAudioRendererSink> NewMixableSink(